Quantitative estrogen receptor values and growth of carcinoma of the breast before surgical intervention.

Quantitative estrogen receptor (ER) values in patients with breast carcinoma were correlated with the natural history of the disease before surgical intervention. The natural history was expressed as an index of growth. This was determined as a ratio between tumor size (centimeters) and duration of symptoms (weeks). An inverse correlation was found between amount of ER and growth. Tumors with high positive (above 101 fmol/mg/protein) ER values has grown significantly slower (P less than 0.05) than tumors with low positive (below 50 fmol/mg protein) or negative ER values. These two latter groups had a similar natural history. Recognition of the fact that there is slow growth in carcinomas with high ER as well as of the fact that growth is as rapid in carcinomas with low ER levels as it is in carcinomas with negative ER values, demonstrates the importance of quantitative ER determinations, their prognostic value, and their usefulness in planning therapy.